U.S. patent application number 10/377365 was filed with the patent office on 2004-09-16 for vehicle sensing system.
This patent application is currently assigned to 3M Innovative Properties Company. Invention is credited to Cybulski, Eric R..
Application Number | 20040178930 10/377365 |
Document ID | / |
Family ID | 32961237 |
Filed Date | 2004-09-16 |
United States Patent
Application |
20040178930 |
Kind Code |
A1 |
Cybulski, Eric R. |
September 16, 2004 |
Vehicle sensing system
Abstract
A reusable mechanical fastening means for a vehicle monitoring
system facilitates maintenance and repair of the system. A
plurality of carrier sections are connected together by clips. The
clips have release tabs to move prongs against a spring force,
thereby making the clips manually detachable. Vehicle sensing
probes have interference ridges which mate with probe openings in
the carrier sections. The carrier sections have open bottoms, and
the worker can overcome the locking force of the interference ridge
by turning the carrier section over and pressing on the probe
through the open bottom. The clips can be attached on multiple
planes relative to the carrier sections, minimizing torsional play
within the extended support train. The clips and carrier sections
are also easily manufacturable.
Inventors: |
Cybulski, Eric R.;
(Woodbury, MN) |
Correspondence
Address: |
3M INNOVATIVE PROPERTIES COMPANY
PO BOX 33427
ST. PAUL
MN
55133-3427
US
|
Assignee: |
3M Innovative Properties
Company
|
Family ID: |
32961237 |
Appl. No.: |
10/377365 |
Filed: |
February 28, 2003 |
Current U.S.
Class: |
340/933 |
Current CPC
Class: |
F16B 7/0406 20130101;
G08G 1/02 20130101; G08G 1/042 20130101 |
Class at
Publication: |
340/933 |
International
Class: |
G08G 001/01 |
Claims
What is claimed is:
1. A system for detecting vehicles on a vehicle travel surface,
comprising: a plurality of support carrier sections adapted for
insertion followed by aligned attachment and sliding within a
conduit extending under the vehicle travel surface, each support
carrier section comprising: a body which is substantially rigid
running longitudinally from a first end to an opposing second end;
a clip recess defined in the body adjacent the first end of the
body; a clip adjacent the second end of the body, the clip having a
prong which deflects against a spring force to be tactilely
receivable in the clip recess of a next aligned support carrier
section; and a release lever for the clip, the release lever
extending upwardly and exposed for manual depression to overcome
the spring force and move the prong to a release position relative
to the clip recess.
2. The system of claim 1, further comprising: at least one sensor
probe releasably attachable to the body.
3. The system of claim 2, wherein each body includes a sensor
opening defined in the body for receiving and holding a sensor
probe, wherein the sensor probe includes an interference ridge
tactilely receivable in the sensor opening.
4. The system of claim 2, wherein each body includes a sensor
opening defined in the body for receiving and holding a sensor
probe inserted from above, and wherein the body allows access to
the sensor probe from below to push the sensor probe upward
relative to the body and remove the sensor probe from the sensor
opening.
5. The system of claim 1, wherein the clip includes a downwardly
directed ramp surface, the ramp surface interacting with the clip
recess of a preceding body to place a gradually increasing force
overcoming the spring force of the clip when the clip is pressed
downward into the clip recess from above.
6. The system of claim 1, wherein each body has a consistent
cross-sectional shape, wherein the clip is separately formed from
the body and attached to the body, and wherein the clip extends
beyond the second end of the body for a sufficient distance so as
to maintain limited separation between adjacent aligned bodies
connected by the clip.
7. The system of claim 6, wherein the attached clip and the limited
separation permit limited pivoting movement of an attached body
relative to a preceding body.
8. The system of claim 1, wherein the release lever is a thumb
lever.
9. A system for detecting vehicles on a vehicle travel surface,
comprising: a plurality of support carrier sections adapted for
insertion followed by aligned attachment and sliding within a
conduit extending under the vehicle travel surface, each support
carrier section comprising: a body which is substantially rigid
running longitudinally from a first end to an opposing second end;
a clip recess defined in the body adjacent the first end of the
body; a clip attached to the body on multiple surfaces, the clip
having a prong adapted to be received in the clip recess of an
adjacent support carrier section for attachment of adjacent support
carrier sections.
10. The system of claim 9, wherein the body comprises: a left clip
abutment wall extending vertically; a right clip abutment wall
extending vertically; and a horizontal clip abutment wall extending
horizontally and integrally connected between the left clip
abutment wall and the right clip abutment wall; and wherein the
clip comprises: a left body abutment wall attached to the left clip
abutment wall of the body; a right body abutment wall attached to
the right body abutment wall of the body; and a horizontal body
abutment wall extending horizontally and integrally connected
between the left body abutment wall and the right body abutment
wall and in contact with the horizontal clip abutment wall; such
that the attachment between the clip and the body minimizes
rotational play between the clip and the body about a longitudinal
body axis.
11. The system of claim 10, wherein clip extends beyond the second
end of the body for a sufficient distance so as to maintain limited
separation between adjacent aligned bodies connected by the clip,
wherein the attached clip and the limited separation permit limited
pivoting movement of an attached body relative to a preceding
body.
12. A method of adjusting a relative location of a sensor probe in
a system for detecting vehicles on a vehicle travel surface, the
system comprising: a support structure extending along a
longitudinal axis within a conduit extending under the vehicle
travel surface; a plurality of sensor probe openings in spaced
locations defined within the support structure; and a sensor probe
positioned within one of the sensor probe openings so as to be
upwardly directed at a first location relative to the vehicle
travel surface; the method comprising: removing the support
structure from the conduit a sufficient distance to permit access
to the sensor probe; pushing on the sensor probe so as to remove
the sensor probe from its sensor probe opening; pushing on the
sensor probe so as to insert the sensor probe in a different sensor
probe opening; and sliding the support structure within the conduit
a sufficient distance to position the sensor probe in a second
location relative to the vehicle travel surface.
13. The method of claim 12, further comprising: prior to removing
the sensor probe from its sensor probe opening, rotating the
support structure about its longitudinal axis so the sensor probe
is downwardly directed, such that the pushing force removing the
sensor probe is downwardly directed.
14. The method of claim 13, further comprising: after removing the
sensor probe from its sensor probe opening, rotating the support
structure about its longitudinal axis to its original orientation,
such that the pushing force inserting the sensor probe in a
different sensor probe opening is downwardly directed.
15. The method of claim 14, wherein the sensor probe includes an
interference ridge tactilely receivable in the sensor opening, such
that inserting the sensor probe in the different sensor probe
opening is accomplished with a tactile click.
16. The method of claim 12, wherein the support structure allows
access to the sensor probe from below to push the sensor probe
upward and remove the sensor probe from the sensor opening.
17. The method of claim 12, wherein the support structure
comprises: a plurality of support carrier sections, each support
carrier section comprising: a body which is substantially rigid
running longitudinally from a first end to an opposing second end;
a clip recess defined in the body adjacent the first end of the
body; a clip adjacent the second end of the support carrier
section, the clip having a prong which deflects against a spring
force to be tactilely receivable in the clip recess of a next
aligned support carrier section; and a release lever for the clip,
the release lever exposed for manual depression to overcome the
spring force and move the prong to a release position relative to
the clip recess; wherein the removing act comprises repeated acts
of: pulling the support structure a sufficient distance out of the
conduit to permit access to a next release lever; and depressing
the accessed release lever and thereby disattaching a support
carrier section from the remaining support structure.
18. A method of manufacturing a support carrier section for use in
a system for detecting vehicles on a vehicle travel surface, the
method comprising: forming a support carrier section body which is
substantially rigid running longitudinally from a first end to an
opposing second end, the support carrier section having clip
attachment area which is open and accessible from a first direction
and from a second direction opposing the first direction; placing a
clip into the clip attachment area from the first direction; and
attaching the clip to the support carrier section body from the
second direction.
19. The method of claim 18, wherein the attaching act is performed
using a rivet applied from the second direction.
20. The method of claim 18, wherein the clip attachment area is a
planar horizontal wall, and wherein the first direction is from
above horizontal wall and the second direction is from below the
horizontal wall.
21. The method of claim 20, wherein the support carrier section
body is formed with a horizontal wall extending between a left
runner and a right runner, and wherein both the left runner and the
right runner extend both above and below the horizontal wall, and
wherein both the left runner and the right runner are formed with
an arcuate outer shape
Description
BACKGROUND
[0001] The present invention relates to the field of sensing
vehicles, and, more particularly, to structures used underneath
roads to sense vehicles traveling on such roads, and to methods of
maintaining those structures.
[0002] Methods and devices for detecting the presence of vehicles
on a street or road are well known. Detecting the presence of a
vehicle is done for a variety of reasons. Vehicles may be detected
to monitor the traffic flow and determine road usage. This
information may be utilized for transportation planning and traffic
light control. Pairs of the sensing devices spaced apart along the
roadway may also be utilized to monitor vehicle speeds.
[0003] Prior art vehicle detection devices include U.S. Pat. No.
3,984,764, U.S. Pat. No. 3,943,399, U.S. Pat. No. 4,449,115, and
U.S. Pat. No. 5,491,475, all of which, if installed after the
roadway is in place, require cutting into the pavement. Such
cutting into the pavement has numerous downsides, further explained
in U.S. Pat. No. 5,850,192 at Column 1, lines 18-57, which lines
are incorporated herein by reference. The system of U.S. Pat. No.
5,850,192 includes attachable sections placed into an under-roadway
conduit. The preferred sections are substantially rounded to be
self-centering and may be weighted to maintain the probes in a
substantially vertically oriented position. The original commercial
implementation of the system of U.S. Pat. No. 5,850,192 included a
clip attached to a carrier from above using blind rivets and
washers.
[0004] However, the system of U.S. Pat. No. 5,850,192 left several
shortcomings. The system of U.S. Pat. No. 5,850,192 is difficult to
assemble due to inherent design constraints. For instance,
installers can attach adjacent carriers of the original system
together without creating a secure positive mechanical lock, and
the connected carriers can become inadvertently detached during
installation. If an installer does accomplish a positive attachment
of adjacent carriers, then disassembly for maintenance and repair
can be quite difficult. The system of U.S. Pat. No. 5,850,192 is
expensive to manufacture. In particular, secondary operations in
the original carrier design cannot be completed inline, but rather
must be performed separately to the individual carrier units.
Secondary operations include punching holes and slots into the
carrier for the carrier clip, sensor, and the mating tongue piece
of another carrier clip. Performing the secondary operations
separately and offline decreases production efficiency, decreases
accuracy between features, and increases costs. The present
invention particularly improves upon the system disclosed in U.S.
Pat. No. 5,850,192, as well as other problems associated with
underground vehicle sensing systems.
SUMMARY
[0005] This invention is a reusable mechanical fastening means for
a vehicle monitoring system. The system particularly allows for
maintenance and repair in a safe and timely manner. The system
includes a plurality of carrier sections connected by clips. In one
aspect, the clips have release tabs to move prongs against a spring
force thereby making the clips manually detachable. In another
aspect, vehicle sensing probes are connected to the carrier
sections with interference ridges, the carrier sections have open
bottoms, and the installation worker can overcome the locking force
of the interference ridge by turning the carrier section over and
pressing on the probe through the open bottom. The clips can be
attached on multiple planes relative to the carrier sections,
minimizing torsional play within the extended support train. The
clips and carrier sections are also easily manufacturable.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Referring now to the drawings, wherein like reference
letters and numerals indicate corresponding structure throughout
the several views:
[0007] FIG. 1 shows a partially broken away side sectional view of
a first embodiment of a vehicle sensing system according to the
principles of the present invention;
[0008] FIG. 2 shows a partially broken away perspective view of a
portion of the vehicle sensing system shown in FIG. 1;
[0009] FIG. 3 shows a cross-sectional view of a probe carrier
support section taken along lines 3-3 of FIGS. 1 and 2;
[0010] FIG. 4 shows a perspective view of the connector clip of
FIGS. 1-3;
[0011] FIG. 5 shows a side view of the connector clip of FIGS.
1-4;
[0012] FIG. 6 shows a perspective view of the sensor of FIGS.
1-2;
[0013] FIG. 7 shows a cross-sectional view of a probe carrier
support section, connector clip and sensor taken along lines 7-7 of
FIG. 2;
[0014] FIG. 8 shows an exploded perspective view of rivet
attachment of a probe carrier support section and connector clip,
showing a second embodiment of a connector clip according to the
principles of the present invention;
[0015] FIG. 9 shows a perspective view of a third embodiment of a
connector clip according to the principles of the present
invention; and
[0016] FIG. 10 shows a plan view of several field assembled carrier
sections.
[0017] While the above identified FIGS. 1-10 set forth preferred
embodiments, other embodiments of the present invention are also
contemplated, some of which are noted in the discussion. In all
cases, this disclosure presents the illustrated embodiments of the
present invention by way of representation and not limitation.
Numerous other minor modifications and embodiments can be devised
by those skilled in the art which fall within the scope and spirit
of the principals of this invention.
DETAILED DESCRIPTION
[0018] Referring now to the drawings, and in particular to FIGS. 1
and 2, there is shown a below ground vehicle sensing system,
generally designated 20. In many respects, the vehicle sensing
system 20 is similar to the vehicle sensing system disclosed in
U.S. Pat. No. 5,850,192 in particular at Col. 3, line 54--Col. 4,
line 55, Col. 5, lines 3-10, Col. 6, lines 9-22, and Col. 6, line
63--Col. 7, line 45 which lines are incorporated herein by
reference. The vehicle sensing system 20 generally is positioned
below a vehicle travel surface or roadway 22, normally pavement
such as concrete or asphalt, and typically at a depth of 16 to 24
inches below the upper surface of the roadway 22. In a preferred
embodiment, a bore or conduit 24 extends horizontally under the
roadway 22 from a surface access hole 26, commonly referred to as a
hand hole, at the side of the roadway 22. The hand hole 26
typically includes a cover 28 to protect the wiring, electronics
and other elements of the vehicle sensing system 20.
[0019] The sensing system 20 includes one or more sensor probes 30.
The probes 30 may be as disclosed in U.S. Pat. No. 5,850,192, or
may sense the presence of vehicles traveling above over the roadway
22 through other means. Multiple probes 30 may be daisy-chain
connected by cable 31, each probe 30 may have a separate cable 31,
or each probe 30 may transmit without cable to a processor or
controller. When the probe 30 senses the presence of a vehicle, a
signal is sent to the processor or other control system (not shown)
for processing, such as traffic light control or other traffic
analysis.
[0020] To function properly, the preferred probes 30 should be
aligned in a substantially vertical orientation, or at least within
10.degree. of vertical. Satisfactory performance may be achieved
when the probe 30 is within 45.degree. of vertical, but the
efficiency and accuracy of the probe 30 tends to decrease when
tilted substantially away from vertical or away from the preferred
design position.
[0021] As shown in FIGS. 1 and 2, each probe 30 is housed in a
probe carrier support section 32 which is further detailed in FIGS.
3, 8 and 10. The probe carrier support section 32 supports and
holds the probe 30 in alignment. The probe carrier support section
32 also protects the probe 30. The system 20 also includes a
plurality of spacer sections 34, which are used to position the
probe carrier support section(s) 32 holding the probe(s) 30 in the
desired transverse position relative to the roadway 22. A plurality
of the spacer sections 34 are connected with probe carrier support
sections 32 to form an extended support train 36 housing one or
more probes 30 in spaced apart relationship. In the preferred
embodiment, the spacer sections 34 are constructed identically to
the probe carrier support sections 32, and the term "carrier
section 32" will be used herein to refer to such sections 32, 34
regardless of whether a probe 30 is being held by the carrier
section 32 or not. Constructing all the carrier sections 32
identically reduces the number of different parts in the system 20,
increases the interchangability of parts, and increases flexibility
in positioning the probes 30. Alternatively, different connector
sections or connector material or other intermediate structures may
be used as spacer sections between probe carrier support sections
as taught in several of the embodiments of U.S. Pat. No.
5,850,192.
[0022] As best shown in FIGS. 3 and 8, each of the carrier sections
32 includes a carrier body 38 preferably with a cylindrical outer
profile 40 which is sized for insertion into the conduit 24. The
carrier body 38 is substantially rigid and runs longitudinally from
one end 42 which is intended to be a leading end to an opposing
(trailing) end 44. The carrier sections 32 each are made up of two
rails or runners 46 on the sides of a frame or mounting portion 48
with an open top portion 50. Both the left runner 46 and the right
runner 46 are formed with an arcuate outer shape to provide the
rounded outer profile 40. The rounded or curved nature of the outer
profile 40 helps to self align each carrier section 32 within the
conduit 24. The low center of gravity for the carrier section 32
biases the carrier sections to naturally achieve proper
orientation. The mounting portion 48 or lower portion of the
carrier section 32 may be weighted to further stabilize the carrier
section 32 and assist in orienting the probe 30 in a substantially
vertical stable position.
[0023] The mounting portion 48 between the two runners 46 includes
orifices or probe mounting holes 52 for receiving and aligning the
probes 30, as shown on FIGS. 1 and 2. The mounting portion 48
includes a horizontal wall 54 extending between the left runner 46
and the right runner 46, with both the left runner 46 and the right
runner 46 extending both above and below the horizontal wall 54. In
this way, the horizontal wall 54 supports the probe 30 in a
protected configuration so the probe 30 is supported in a central,
sheltered position in the conduit 24. The mounting portion 48
includes two generally planar, upright vertical walls 56 and the
horizontal wall 54 running between the vertical walls 56. The
planar nature of the vertical walls 56 make them quite strong and
robust to withstand years of use, with changes due to environmental
and weather conditions, without gravitational sagging, warping,
deflection or degradation which may cause a sensor probe 30 to come
out of alignment. In the preferred embodiment, each of the right
and left runners 46, the vertical walls 56 and the horizontal wall
54 are formed at a thickness of about 0.100 inches, extending for a
section length of about 12 inches. The curvature of the runners 46
defines an outer diameter for the cylindrical outer profile 40 of
about 1.2 inches.
[0024] The (leading) end 42 of the carrier body 38 includes a clip
attachment area 58 preferably provided by a leading, clip abutment
portion of the vertical walls 56 and the horizontal wall 54. The
open top portion 50 permits access to the clip attachment area 58
from above. The carrier body 38 has an open bottom 60 which permits
access to the underside of the clip attachment area 58 from
below.
[0025] The horizontal wall 54 of the mounting portion 48 could
include a single mounting hole. More preferably the horizontal wall
54 includes two or more probe mounting holes 52 in spaced apart
relationship so that the spacing of the probes 30 may be varied to
accommodate probe spacing specifications. During assembly and use,
the open top portion 50 receives a portion of the probes 30 mounted
in mounting holes 52, and also receives the runs of cable 31. The
open bottom 60 of the carrier body 38 permits access to the
mounting holes 52 from below and permits access to any probes 30
extending through the mounting holes 52 from below.
[0026] The horizontal wall 54 of the mounting portion 48 includes a
clip recess or opening 62 formed toward the (trailing) end 44, with
a connector clip 64 attached to the other (leading) end 42. While
the clip recess 62 could be formed in any trailing portion of the
carrier body 38, it should be placed to properly align and mate
with the connector clip 64.
[0027] The mounting portion 48 includes two recessed retention
grooves 66, one in each of the vertical walls 56. In the preferred
embodiment, the recessed retention grooves 66 run the full length
of the carrier section 32, measuring 0.020 inches deep (i.e., 20%
of the wall thickness) by 0.105 inches in height. The recessed
retention grooves 66 can be used to secure a metal connector clip
64 or sensor probe 30 in place without using any tools or adding
additional parts such as screws, washers, or nuts, and punching.
Avoidance of screws, washers and nuts as well as minimizing further
manufacturing steps such as punching not only reduces manufacturing
costs, but also prevents accidental damage to the inside of the
mounting portion 48. The retention grooves 66 are squared off so as
to more tightly mate with side tabs 68 of the connector clip
64.
[0028] The open cross-sectional top area 50 of the carrier body 38
is larger than in the original design of U.S. Pat. No. 5,850,192.
This larger open top area 50 more easily holds and protects the
cables 31. The larger open cable run area 50 also allows longer
runs to be installed because more sensor probes 30 and accompanying
cables 31 can be protected inside the carrier section 32.
[0029] The preferred method of manufacturing the carrier sections
32 is through extrusion of a plastic material. Each body 38 has a
consistent cross-sectional shape throughout its length, which
facilitates extrusion. As an extrusion, the outer runners 46 and
the mounting portion 48 are integrally formed as a single element.
Alternatively, the runners 46 and the mounting portion 48 may be
attached in other ways. The plastic material is substantially
rigid, and the cross-sectional shape helps to provide additional
rigidity, particularly against torsional deflection when torqued
about a longitudinal axis. The plastic material resists corrosion
and is rugged and robust. Because the carrier sections 32 have a
generally consistent cross-sectional shape, plastic extrusion can
be accomplished at relatively low cost. The preferred plastic is a
high modulus material, and most preferably rigid PVC or ABS.
[0030] The openings 52 for the sensor probe 30, as well as any
rivet openings 70, can then be added in a secondary operation, such
as machining or more preferably punching into the extrusion. The
straight vertical walls 56 of the mounting portion 48, with no
undercut, absorb the stress of the punching operation much better
than the prior art design. The open bottom 60 of the mounting
portion 48 also permits bottom access during the punching
operation, to better support the mounting portion 48 during
punching. Stress and damage to the extrusion during the punching
process are therefore largely avoided. Greater locational accuracy
for the punching operation can also be obtained in a jig by
aligning the two rails of the carrier section 32 relative to the
jig and having access through the open bottom 60 to the underside
of the mounting portion 48. With the design of the present
invention, the secondary operations are relatively simple, and can
be completed inline with the extrusion.
[0031] Each carrier section 32 includes a connector clip 64 which
mounts at one end 42 of the carrier body 38. As shown in FIGS. 1,
2, and 10, the connector clip 64 attaches to the next adjacent
section 32 to hold the carrier sections 32 in a connected
arrangement and angularly aligned. As best shown in FIGS. 4 and 5,
the connector clip 64 includes a retaining section or prong 72
which engages the clip recess or slot 62 formed in the preceding
carrier section 32. The prong 72 extends beyond the (leading) end
42 of the carrier body 38 for a distance slightly greater than the
distance that the clip recess 62 is removed from the (trailing) end
44 of the carrier body 38. In the preferred embodiment, the clip
recess 62 is removed about 1.00 inches from the (trailing) end 44
of the carrier section 32, and the connector clip 64 is positioned
so the prong 72 extends 1.10 inches from the (leading) end 42 of
the carrier section 32, thereby maintaining a separation of about
0.10 inches between adjacent aligned carrier bodies 38 connected by
the connector clip 64. Of course, the designed 0.10 inch separation
is subject to manufacturing tolerances, which tolerances should be
sufficiently tight so there is never an overlap or negative
separation between attached adjacent aligned carrier bodies 38.
[0032] The connector clip 64 includes a positive mechanical locking
feature, best shown in FIG. 5. The width of the prong 72 is defined
by two opposing spring legs 74. The spring legs 74 have a shoulder
76 which defines an uncompressed spring width which is greater than
the width of the clip recess 62. In the preferred embodiment, the
clip recess 62 has a width of 0.200 inches, while the uncompressed
width of the spring legs 74 at the shoulder 76 is 0.274 inches. The
spring legs 74 compress together to a minimum width of 0.178
inches. The outer spring leg 74 provides a downwardly directed ramp
surface 78 which extends at a ramp angle of 14.degree. to vertical.
When the prong 72 is pushed downward into the clip recess 62, the
ramp surface 78 causes the recess wall to gradually increase its
force and press the outer spring leg 74 toward the inner spring leg
74, decreasing the width between spring legs 74 to a value less
than the 0.200 inch opening of the clip recess 62. Once fully
inserted, the outer spring legs 74 snaps into position with a
tactile click to secure the connector clip 64 into the clip recess
62. The spring force and shoulder 76 then positively holds the
connector clip 64 in place, and thus secures the carrier sections
32 together.
[0033] The connector clip 64 is designed with a quick release thumb
tab 80, best shown in FIG. 5. The term "thumb tab", as used herein,
refers in general to a size adequate to allow manual hand
depression, without the use of a tool, by a workers thumb or
fingers. In the preferred embodiment, the thumb tab 80 is
appropriately sized for manual hand depression by having an exposed
width of at least 0.20 inches and an exposed height of at least
0.20 inches, with the most preferred size being a width of 0.75
inches and extending about 0.40 inches above the horizontal wall 54
of the mounting portion 48. The quick release tab 80 can easily be
activated to detach the carrier sections 32 in the field without
the use of tools. Easy detachment and removal of the carrier
sections 32 is particularly important during the maintenance and
repair periods. Each connector clip 64 needs to readily detach from
the preceding carrier section 32 to facilitate removal, such as in
the event that there is a malfunction in a sensor probe 30 which is
used to sense the flow of traffic.
[0034] The connector clip 64 includes a left body abutment wall 82,
a right body abutment wall 84, and a horizontal body abutment wall
86 extending horizontally and integrally connected between the left
body abutment wall 82 and the right body abutment wall 84. The left
and right body abutment walls 82, 84 can include side tabs 68 sized
and spaced to mate with the retention grooves 66 of the carrier
sections 32. The side tabs 68 can run the entire length of the
abutment walls 82, 84 as shown in the preferred embodiment of FIG.
4. Alternatively, the side tabs 68 can run only a portion of the
connector clip length as shown in the embodiment of FIG. 8. Another
alternative configuration of side tabs 68 could be two shorter tabs
on each side instead of one longer tab on each side.
[0035] If desired, the connector clip 64 can be manufactured
integrally with the carrier body 38. However, the preferred
embodiment separately forms the connector clips 64 of a different
material and a different process than the extruded plastic carrier
bodies 38. In a preferred embodiment, the connector clip 64 is a
corrosion resistant metal material, such as 300 series stainless
steel, annealed. When formed of steel, the connector clip 64 can be
stamped and folded from 0.032 inch thick sheet steel, which
provides an acceptable spring force for the prong 72 and can
satisfactorily transmit torsion and pull forces between attached
carrier sections 32. When formed of metal, the side tabs 68 which
extend less than full length can be half-shear tabs or triangular
tabs which pierce into the carrier body 38. Alternatively, the
connector clips 64 could be molded out of plastic.
[0036] Assembly of the connector clip 64 to the carrier body 38 is
simpler and less costly than the prior art. The connector clip 64
is placed onto the clip attachment area 58 from above. The side
tabs 68 of the preferred connector clip 64 mate with longitudinal
grooves 66 on the carrier section 32, such that the right body
abutment wall 84 of the connector clip 64 is attached to the right
vertical wall 56 of the carrier body 38 and the left body abutment
wall 82 of the connector clip 64 is attached to the left vertical
wall 56 of the carrier body 38. By connecting the connector clip 64
to the carrier body 38 on multiple surfaces and in multiple planes,
the side tabs 68 serve several purposes. First, the side tabs 68
prevent any up or down movement of the connector clip 64 relative
to the carrier body 38. Second, the side tabs 68 also add strength
to the abutment walls 82, 84 of the connector clip 64 to allow for
the clockwise and/or counter-clockwise twisting action to occur
without damage to the assembly, such that the attachment between
the connector clip 64 and the carrier body 38 minimizes rotational
play between the connector clip 64 and the carrier body 38 about a
longitudinal body axis.
[0037] If an even more secure attachment between each connector
clip 64 and its carrier body 38 is desired, semi-tubular rivets 88
can be used, either in conjunction with or in place of the side
tabs 68. With the carrier sections 32 formed of a high modulus PVC
material and with access through the open bottom 60 to the bottom
surface to which the rivets 88 are attached, conventional riveting
can be used. Two washers which were used in the original commercial
embodiment to help secure the connector clip on to the carrier
section are eliminated. Access to the clip attachment area 58 from
both above and below now facilitates fastening of the connector
clip 64 to the carrier section 32 from above and below by using
semi-tubular rivets 88. This has eliminated the need for using
blind rivets and has eliminated the need for a washer to retain
each rivet in place. When both tabs and rivets 88 are used, the
tabs are preferably in the plane bisecting the rivets 88 thereby
providing maximum in line support.
[0038] As an alternative to rivet attachment, the connector clip 64
can be formed with other tabs which are bent underneath the wall of
the carrier extrusion during a secondary operation. Such an
operation is possible again because the clip attachment area 58 is
accessible from both above and below. Eliminating the need for
rivets reduces the cost of the carrier assembly.
[0039] As an alternative to any type of permanent attachment of the
connector clip 64 to the carrier member, the connector clip 64 may
snap on to both carriers as shown in FIG. 9. Such a dual snap
construction will further reduce manufacturing costs, but could
introduce additional assembly steps and disassembly problems in the
field. All of these alternatives avoid the use of adhesives or
tapes (which can degrade over extended times in harsh environmental
conditions), or other types of mechanical fasteners such as screws
or nuts and bolts (which can increase assembly time).
[0040] While the present invention is in no way limited to the type
of sensor probe 30 used, the present invention further contemplates
structures for readily attaching and detaching the sensor probe 30
to the carrier section 32. As best shown in FIGS. 6 and 7, the
sensor probe 30 includes an interference ridge 90. The interference
ridge 90 is sized and spaced to mate with the sensor openings 52 in
the horizontal wall 54. In the preferred embodiment, the sensor
opening 52 is sized with a slight clearance such as 0.012 inches in
diameter greater than the outer diameter of the sensor probe 30,
and the interference ridge 90 is then sized at an increased
diametrical thickness of 0.016 inches relative to the outer
diameter of the sensor probe 30, causing a 0.004 inch interference
during insertion of the sensor probe 30 into the sensor opening 52.
The preferred interference ridge 90 extends axially for a length of
0.043 inches along the sensor probe 30.
[0041] Each sensor probe 30 is pressed into its sensor opening 52
from above. Once the interference ridge 90 passes fully through the
sensor opening 52, the sensor probe 30 seats in the sensor opening
52 with a strong positive mechanical attachment which provides a
tactile click. Because only a push force and no pull force is used
to seat the sensor probe 30, the likelihood of damage to the sensor
probe 30 during the seating process is minimized. The tactile click
obtained when the sensor probe 30 is fully seated further minimizes
the possibility of damage due to too large of a compression force
pushing the sensor probe 30 into the sensor opening 52. Such
possibility of pulling damage or over-pushing damage are
particularly to be avoided in that the attachment of the sensor
probe 30 to the carrier section 32 is commonly performed in the
field during installation of the system 20 and under diverse
weather and environmental conditions, as contrasted from assembly
in a controlled assembly plant environment.
[0042] The preferred sensor probe 30 has a housing body 92 molded
of generally rigid plastic, such as ABS. As a molded article, the
tolerance of the interference ridge 90 can be closely
maintained.
[0043] Assembly and placement of the probes 30 and the vehicle
sensing system 20 is even more easily accomplished and simple than
with the system of U.S. Pat. No. 5,850,192. Once the bore is formed
and a conduit 24, if used, is inserted, the support structure 36
and the probes 30 are placed. To begin insertion, the first carrier
section 32 is placed into the hand hole 26 and linearly aligned to
the conduit 24. The first sensor probe 30 is inserted from above
into a sensor mounting hole 52 in the carrier section 32. The
installer presses the sensor probe 30 downward until a tactile
click is registered, verifying that the sensor probe 30 is fully
seated. The associated wiring cable 31 (if any) for the sensor
probe 30 is fed backward toward the open (trailing) end 44. If
desired, a retrieval line 94 may be connected to the first carrier
section 32 and extended backward. When this step has been
completed, the carrier section 32 in its linear alignment with the
conduit 24 is pushed forward and slid into the conduit 24 until
sufficient room in the hand hole 26 for a next carrier section
32.
[0044] The next carrier section 32 is placed downward onto the
first carrier section 32, aligned so that the prong 72 of the
connector clip 64 engages downwardly into the clip recess slot 62
in the horizontal wall 54 of the first carrier section 32. The
installer presses the next carrier section 32 downwardly until the
clip prong 72 springs outward into engagement with the slot 62 and
the spring action registers a tactile click perceived by the
installer that the two carrier sections 32 are fully clipped
together. Considering that this attachment will necessarily occur
within the hand hole 26, the use of only downward force is much
simpler for the installer than pulling upward. The second carrier
section 32 is pushed forward into the conduit 24 and the
attachment/assembly process is continued by the installer.
[0045] The wiring 31 of the sensor probe(s) 30 is placed through
the open top 50 of the second carrier section 32 and the retrieval
line 94 is also placed over the open top 50 in the carrier section
32. If spacing to achieve a desired detection coverage area
dictates that another probe 30 should be placed in a carrier
section 32, the probe 30 is inserted into one of the mounting holes
52. Typically, an additional sensor probe 30 will be used for each
lane of traffic being monitored. When this step has been completed,
the connected carrier sections 32 are pushed forward into the
conduit 24. As additional carrier sections 32 are attached, the
extended support train 36 grows in length. This process is repeated
until an extended support train 36 is assembled with sufficient
carrier sections 32 aligned in an end-to-end configuration within
the conduit 24 so that the sensor probes 30 are positioned at their
predetermined sensing locations beneath the roadway 22.
[0046] Typically, each sensor probe 30 will be centered beneath the
lane of traffic being monitored. If desired, the distance to the
endmost sensor probe 30 may be measured above ground from the hand
hole 26 to the desired center-of-lane position, and sufficient
support carrier sections 32 may be assembled until the end probe 30
is placed at the proper, measured position beneath the roadway 22.
The distance back from which a sensor probe 30 needs to be placed
from the first carrier section 32 may be marked on the retrieval
line 94 or on the wiring 31 and a probe 30 inserted into the
carrier section 32 proximate each pre-measured position. In this
manner, easy installation is provided for following placement of
the first endmost probe 30.
[0047] To properly align the sensor probe(s) 30 in vertical
orientation, the installer will take the exposed carrier section 32
(the most recently installed carrier section 32) and twist it in
either a clockwise or counter-clockwise direction about the
longitudinal axis of the conduit 24. Adjustment is achieved by
creating a pulling, pushing, or twisting in a clockwise or
counterclockwise motion, or any combination thereof to align the
sensors 30 inside the conduit 24 as necessary. The connector clips
64 need to be capable of withstanding this twisting force without
separating from the individual carrier sections 32. The retention
slot/tab attachment between the connector clips 64 and the carrier
sections 32 is quite robust, and greatly diminishes the occurrence
of having a connector clip 64 separate from its carrier section 32
during use. Because each connector clip 64 is preferably attached
to its carrier sections 32 along two or three planes, when the
linked carrier sections 32 are torqued about the longitudinal axis
by the installer, the connector clips 64 do not bend but remain
rigidly attached to the carrier sections 32. This design of the
connector clips 64 minimizes the amount of torsional or rotational
play between linked carrier sections 32, so all the sensor probes
are equivalently aligned and rotation of the last carrier section
32 about its longitudinal axis equivalently rotates all of the
attached carrier sections 32 in the extended support train 36. If
desired, a cradle clip (not shown) may finally be used to secure
the angular orientation of the connected carrier sections 32 and
sensor probes 30 within the conduit 24 and at the substantially
vertical orientation relative to the longitudinal axis of the
conduit 24. As a final step, the wiring 31 is then fed to the
proper processors for data analysis, which may either be placed at
the hand hole 26 or placed remotely therefrom.
[0048] In an ideal world, the system 20 of the present invention is
installed prior to laying the roadway 22. Prior to creation of the
roadway 22, the system 20 can be installed and the flatness of the
conduit 24 can be measured and maintained quite precisely. The
result is a conduit 24 under the roadway 22 which is very straight,
flat and clean. However, many roadways 22 were created before the
need to monitor traffic was determined, and the system 20 of the
present invention is commonly useful in monitoring traffic
traveling on such pre-existing roadways 22. When the roadway 22 is
pre-existing, conduit 24 is bored horizontally into place under the
roadway 22 by use of a hydraulic ram. However, horizontal boring is
not as accurate as the preconstruction open trench system, and the
result is a conduit 24 which may bend along its length. Similarly,
a slight bend radius may occur because continuous conduit is
supplied to the installation crews on large rolls or spools, and
the conduit may take a natural curl or bend from its previous spool
wrapping.
[0049] The design of the present invention particularly
contemplates use with conduits 24 which include such a bend. The
connector clip 64 is attached to the carrier body 38 such that the
prong 72 extends beyond the (leading) end 42 of the carrier body 38
for a sufficient distance so as to maintain limited separation
between adjacent aligned bodies 38 connected by the connector clip
64. In particular, the length of the connector clip 64 of the
present invention is slightly longer than the corresponding length
between attachment points on the two carrier sections 32 as shown
in FIG. 10, such that the attached carrier sections 32 have a
slight gap 96 between them. The leading carrier section 32 has the
same cross-sectional shape at its trailing end 44 as the
cross-sectional shape of the trailing carrier section 32 at its
leading end 42. The slight gap 96 permits a limited amount of
pivoting between attached carrier sections 32. In the preferred
embodiment, a designed gap 96 of about 0.10 inches allows pivoting
of up to 5 to 15.degree.. This allows the attached carrier sections
32 to negotiate a bend in the conduit 24 which corresponds in
amount of bend and severity of bend to the associated radius of
curvature created by 5 to 15.degree. angles between rigid attached
carrier sections 32. A gap larger than 0.10 inches may allow even
greater flexibility. While the preferred connection clip attachment
permits this pivoting, it still prevents significant torsional or
rotational play. The cross-sectional shape of the preferred carrier
design can thus accommodate larger variations in the flatness and
bend of the buried conduit run than could be accommodated by the
prior art. As carrier sections 32 are inserted into the conduit 24,
the extended support train 36 bends slightly so the sides of the
carrier sections 32 do not get caught on the conduit joints or bind
against the conduit inner diameter.
[0050] Rocks and other debris can become trapped in the conduit 24.
The open bottom 60 under the carrier section 32 provides for a
place for rocks and other debris to position themselves as the
carrier sections 32 are inserted into the conduit 24. Problems
associated with blowing rocks and other debris out with compressed
air or pulling them out are avoided.
[0051] Should maintenance or adjustment be required, such as in the
event a faulty sensor probe 30 needs to be replaced, the present
invention provides great benefits over the prior art. The extended
support train 36 can be pulled outward toward the hand hole 26 by
pulling on the last carrier section 32 or by pulling the carrier
sections 32 back with the retrieval line 94. Once a carrier section
32 is sufficiently within the hand hole 26 to permit access to the
thumb tab 80, the worker depresses the quick release thumb tab 80
without the aid of additional tools and pulls the carrier section
32 upward, unclipping the end most carrier section 32 from the next
adjacent carrier section 32. The quick release thumb tab 80 acts as
a lever to provide for a large moment force which is used to
overcome the spring force of the prong 72. Note that the quick
release thumb tab 80 detaches by pressure in a direction out of the
conduit 24, so there is no danger that the thumb tab 80 will catch
on the conduit 24 and release during pulling the extended support
train 36 from the conduit 24. The thumb-sized release tabs 80
require less worker applied force and allow the worker to readily
separate adjacent carrier sections 32 when desired.
[0052] The sensor probes 30 can also be much more readily removed
from the carrier sections 32 than was possible with the prior art.
The worker can either pull the extended support train 36
sufficiently from the conduit 24 that the sensor probe 30 is within
the hand hole 26 or completely remove the sensor carrying carrier
section 32 from the hand hole 26. The worker then rotates the
carrier section 32 upside down (i.e., generally 180.degree. about
its longitudinal axis). The worker then pushes downwardly on the
sensor probe 30 so as to move the interference ridge 90 through its
sensor probe opening 52, thereby removing the sensor probe 30 from
the carrier section 32. The worker then rotates the carrier section
32 back to its upright orientation. At this point, either a new
sensor probe 30 (if the sensor probe 30 malfunctioned) can be
pushed downward into position in the carrier section 32, or the
same sensor probe 30 (if the sensor probe 30 was improperly
positioned) can be pushed downward into a different sensor opening
52. Once the sensor probe 30 is received back in place with the
desired tactile click, the worker slides the support structure into
the conduit 26 a sufficient distance to position the sensor probe
30 in its desired location relative to the roadway 22. Thus, the
inventive method applies only direct pressure on the sensor probes
30. Workers are not frustrated either with the difficulty of
removing a sensor probe 30 from its carrier section 32 or with
uncertainty as to whether the sensor probe 30 is sufficiently
seated. Most importantly, the workers are not tempted to pull the
sensor probe 30 by its cable 31 and damage the cable 31 or sensor
probe 30 during installation. If the worker so chooses, the entire
sensor probe removal and insertion process can be accomplished
within the hand hole 26, with the worker applying only downward
forces.
[0053] It is to be understood, however, that even though numerous
characteristics and advantages of the present invention have been
set forth in the foregoing description, together with details of
the structure and function of the invention, the disclosure is
illustrative only. Workers skilled in the art will recognize that
changes may be made in form and detail without departing from the
spirit and scope of the invention.
* * * * *